Hack the Underlying Structure of Music with the Circle of Fifths

The circle of fifths is a powerful tool that will help you understand music. If you don't know much about music theory, this circle is an excellent way to start diving into this beautiful world.

What is the circle of fifths?

As the name suggests, it is a circle composed of fifths. In other words, if you start with C and add a perfect V (7 semitones), you get G. If you add a perfect V, you get D, then A, until you met C again. From V to V, you create a circle.

If you don't know/remember what a perfect V is, check out our dedicated article about intervals.

This can be easier to understand with a graphic example 👇

🗺️ More than a circle, it's a map

I like to think of the circle of fifths as a map. Depending on how we read it, though, we get different information. Today I will demonstrate two interpretations that I find helpful. Do remember though that these are not the only possible interpretations.

I. Tones & Key

The circle is really handy as it shows us how the tones and keys are composed.

Let's take the circle and add the key signature for each tone.

Clockwise, a # is added to each step of the circle, while keeping the alterations of the previous steps.

For example, C major does not have any alterations. Then G major has one alteration: F#. Then D has F# but also C#, and so on.

Counterclockwise, the same goes for the flat alterations.

For example, C major does not have any alterations. Then F major has one alteration: Bb. Then Bb has Bb but also Eb, and so on.

To understand how symmetrical and useful this circle is, see the images below.

Note: The blue circle is located on the key, and the stars are on the accidentals corresponding to that key; for the key of D major, accidentals are on the F and C.

The same thing happens with the keys with flat accidentals.

Note: The green circle is located on the key, and the stars are on the alterations corresponding to that key.

Bear in mind that a key always has the same alterations in the same place. For example, the E major key has the alterations: F# C# G# D#. It will never be F#G#C#D# or C#D#F#G#. The magic of the circle works again.

Did you notice that the accidentals are added in fifths as well?

For scales with sharps, accidentals are added in ascending fifths. For scales with flats, the accidentals are added in descending fifths.

What about the relative minor scales?

You may be wondering about the relative scales. Well, the circle of fifths works the same way for those scales. Let's add the relative scales to the circle.

💡Remember each major scale has a minor relative scale

Why is this so useful?

If you see a score now, you can easily find out what the key is.

For example, if you see a score with four sharps in its key signature, you will know that it is either in E major or its relative C#minor . If you want to be certain that it's in the major or minor key, you have to identify the root chord used in the song. A simple way to find out is to look at the last chord in the score. This method works for simple scores, although it's not the most accurate way to do it. But if you are just starting to learn music, the circle of fifths lets you make a good guess 👌.

II. Chords

✨This function is my favorite✨

The circle of fifths shows you which chords belong to each key.

For example, the key G major, or its relative minor E minor, has the following chords:
G - Am - Bm - C - D - Em - Fdim

With the circle, you can easily visualize it all. You need to create a triangle centered in G and add an appendix in the minor chord following the triangle, bearing in mind that the appendix will be dim and not m. See the image below to help you understand :)

Can you see it?

The key is G major or its relative E minor, and the chords are:

• G major: G - Am - Bm - C - D - Em - Fdim
• E minor: Em - Fdim - G - Am - Bm - C - D

This rule applies to all keys.

Below you will find two more examples.

Example 1:

Key: E major or C#minor (relative)

Chords:

• E major: E - F#m - G#m - A - B - C#m - D#dim
• C#minor: C#m - D#dim - E - F#m - G#m - A - B - C#m - D#dim

Example 2:

Key: Bb major or G minor (relative)

Chords:

• Bb major: Bb - Cm - Dm - Eb - F - Gm - Adim
• G minor: Gm - Adim - Bb - Cm - Dm - Eb - F

🤩 Isn't it magical?

There are many other ways to read this map, giving us different information about the underlying structure of music. I invite you to explore it further and make the most of it. -> So jump onto Flat and explore these examples in your compositions!

See you next time,